Correlation of ZnO orientation to band alignment in p-Mg0.2Ni0.8O/n-ZnO interfaces

Abstract

We have investigated the influence of ZnO orientation on the valence band offset (ΔEV) of Mg0.2Ni0.8O(111)/ZnO (112¯0) and Mg0.2Ni0.8O(111)/ZnO(0002) heterostructures by x-ray photoelectron spectroscopy. Combining with the experimental optical energy band gap extracted from UV-vis transmittance spectra, the energy band alignment at the interfaces has been determined. The ΔEV has been found to be 1.8 ± 0.1 eV and 1.4 ± 0.1 eV for Mg0.2Ni0.8O(111)/ZnO (112¯0) and Mg0.2Ni0.8O(111)/ZnO(0002), respectively. Both the heterostructures show type-II band configurations with conduction band offsets (ΔEC) of 2.4 ± 0.1 eV and 2.0 ± 0.1 eV, respectively. The ZnO orientation correlated electronic structure in p-Mg0.2Ni0.8O/n-ZnO interfaces can be explained well by the effect of spontaneous polarization in ZnO. Furthermore, the results offer opportunity that desired band offsets in MgxNi1−xO/ZnO heterostructures can be obtained by appropriately adjusting Mg composition.

Band alignment at the interface between Ni-doped Cr2O3 and Al-doped ZnO: implications for transparent p–n junctions

“…In particular, its large exciton binding energy (60 meV at room temperature) makes this material interesting for application in light emitting diodes (LEDs) [9,12,13]. In this context much attention has been devoted to understand the properties (work functions, ionization potential, band gaps, bend bending) of the different polar and non-polar surfaces in which ZnO can either be grown or cleaved and how they affect the performances of devices [14][15][16][17][18][19][20].…”

“…Despite the considerable effort, homojunctions have proven difficult, mainly due to the lack of reliable and reproducible p-type ZnO [10][11][12][13]. For this reason, heterojunctions comprised of ZnO and suitable p-type transparent semiconducting oxides (TSOs) have been considered [20][21][22][23][24][25][26][27].…”